Skip to main content

ACCUEIL > Nos actualités > > SDN (SD-LAN) vs SDN-WAN: the devil in the detail

SDN (SD-LAN) vs SDN-WAN: the devil in the detail

CLately, we have had our eyes on SD-WANs. It is becoming for networks what the Cloud has become for infrastructures and applications. Yet, while the concept of a software-defined wide area network (SD-WAN: Software Defined Wide Area Network) is generally understood, it is often confused with its technological parent, the software defined network (SDN: Software Defined Network).

So, how can these technologies be so similar and yet so different?

SDN and SD-WAN are almost identical twins:

SDN and SD-WAN are based on the same methodology of separating the control plane from the data plane to make the network more intelligent. Like identical twins, they may look alike, but they are quite different from each other. The main difference between SDN and SD-WAN is in their use.

While SDN addresses the modern networking needs of managing local area networks (LANs) or operator main networks, SD-WAN is used to connect geographically distributed locations and remote users. SDN and SD-WAN can be virtualized to implement additional virtual network functions (VNFs), such as security capabilities and WAN optimization.

The distinctions between SDN and SD-WAN

SDN is fully programmable by the customer or user and offers efficient change and configuration management. While SD-WAN is built on SDN technology, the programming is managed in the background by the SD-WAN provider, eliminating complexity for the end user.

SDN focuses on the internal network, whether this is the local network or the service provider main network, while SD-WAN focuses on enabling connections between networks and users across the WAN.

SDN is enabled by NFV (Network Function Virtualization), providing multiple virtualized network functions via software that was previously embedded in closed proprietary systems. In contrast, SD-WAN provides software-defined application routing that can be virtualized and run either virtually or on an SD-WAN appliance.

Software Defined Network (SDN)

Software Defined WAN (SD-WAN)

Manages a local area network or a service provider core network

Enables connections between networks and users across geographical areas 

User-programmable to provide bandwidth on demand

Programmable to provide operational simplification, built-in security and traffic prioritization

Similar separation of the control plane and the data plane

Similar separation of the control plane and the data plane

Provides main network performance visibility and real-time analytics

Provides WAN environment visibility and real-time analytics

Provides a centralized view for network service automation 

Focuses on software-defined application routing capabilities


SD-WAN takes you from the packet world to the application world and beyond

The technology behind SD-WAN changes the paradigm from a packet-based network routing system to an application-based routing system. This enables organizations to use consumer broadband Internet with improved quality and performance, and most importantly, a lower cost per megabyte than previously available with MPLS.

SD-WAN also provides agility and flexibility, while maintaining centralized predefined company policies controlling how applications are routed. The resulting visibility and control enable you to identify applications running over the WAN and to define policies on their prioritization and use.

SD-WAN also uses dynamic WAN selection to route these applications over the highest performing paths. In addition, SD-WAN allows you to use multiple available links in an "active/active" configuration to provide load balancing and failover, with little to no perceived outage. Traffic between sites travels over dynamic, fully encrypted tunnels and can be segmented, providing a very high level of security.

Enjoy the best of both worlds

For large companies with an increasingly distributed and complex IT infrastructure, the challenge is to manage the network with full visibility, while having the scalability to grow and achieve new business objectives.

With the adoption of cloud-based applications and services, businesses are shifting more of their IT capital expenditure (CAPEX) to operational expenditure (OPEX). As businesses expand, MPLS is simply too costly to scale their WAN infrastructure and does not offer the flexibility to deploy remote services.

The combined use of SDN and SD-WAN can support a company's Cloud-First strategy. Businesses can leverage an SDN platform to interconnect global data centers and connect directly to the cloud via a private carrier Ethernet network fabric, and simultaneously reduce WAN complexity by using an SD-WAN overlay to simply extend the perimeter to multiple branch offices and remote users in a secure and orchestrated way.

Before choosing a network solution for your evolving company, don't hesitate to discuss it with the Numeryx team. We can help you determine the best solution for your network architecture needs and provide the best thinking on how SDN and SD-WAN will impact your applications and overall security policy.


Ahmed B
Ahmed B.